Pat Patwardhan knew something was wrong with his health, but it took several weeks and several tests to get a diagnosis. After determining he was suffering from heart failure, Patwardhan was asked to participate in a new study to see if researchers could detect the condition in his breath. That test was easy. The machine is part of a new generation of diagnostic devices that promise to potentially sniff out all sorts of diseases, including various cancers, liver disease, kidney failure, diabetes, asthma and tuberculosis.